Ultrastructure Of Secretory Cells Research Articles

An ultrastructural study of the development of resin canals and lacquer secretion in Toxicodendron vernicifluum (Stokes) F.A.Barkley

Raw lacquer is a natural resin obtained by tapping the secondary phloem of oriental lacquer trees (T. vernicifluum), and the secretory cells of the resin canals play an important role in raw lacquer production. The objective of this study was to perform a detailed analysis of the anatomy and ultrastructure of the secretory cells, to investigate the structural characteristics and ontogeny of secretory cells, and study the synthesis and secretion of raw lacquer. This cytological study on the structure of secretory cells and the secretion of raw lacquer were investigated using alight microscope (LM) and transmission electron microscope (TEM).The results showed that the resin canals was formed by the initial cells of secretory cells through schizogeny. Secretory granules with monofilm were shaped by Golgi bodies and transported to the plasma membrane. Thereafter, the granules were fused with the cell membrane, and the interior flocculent materials were released to the periplasmic space and spread to the resin canals through the cell walls of secretory cells. Finally, the cells fused and gathered in the lumen to form raw lacquer. The present study offers detailed information on the ultrastructure of secretory cells and the process of raw lacquer secretion.

Floral nectar production and carbohydrate composition and the structure of receptacular nectaries in the invasive plant Bunias orientalis L. (Brassicaceae)

The data relating to the nectaries and nectar secretion in invasive Brassicacean taxa are scarce. In the present paper, the nectar production and nectar carbohydrate composition as well as the morphology, anatomy and ultrastructure of the floral nectaries in Bunias orientalis were investigated. Nectary glands were examined using light, fluorescence, scanning electron and transmission electron microscopy. The quantities of nectar produced by flowers and total sugar mass in nectar were relatively low. Total nectar carbohydrate production per 10 flowers averaged 0.3 mg. Nectar contained exclusively glucose (G) and fructose (F) with overall G/F ratio greater than 1. The flowers of B. orientalis have four nectaries placed at the base of the ovary. The nectarium is intermediate between two nectary types: the lateral and median nectary type (lateral and median glands stay separated) and the annular nectary type (both nectaries are united into one). Both pairs of glands represent photosynthetic type and consist of epidermis and glandular tissue. However, they differ in their shape, size, secretory activity, dimensions of epidermal and parenchyma cells, thickness of secretory parenchyma, phloem supply, presence of modified stomata and cuticle ornamentation. The cells of nectaries contain dense cytoplasm, plastids with starch grains and numerous mitochondria. Companion cells of phloem lack cell wall ingrowths. The ultrastructure of secretory cells indicates an eccrine mechanism of secretion. Nectar is exuded throughout modified stomata.

The structure of floral nectaries of some species of Vicia L. (Papilionaceae)

The subject of research were morphology and ultrastructure of floral nectaries of nine species of <i>Vicia</i>. The differences in their size and morphological structure were shown. Small, almost flat nectaries appeared in flowers of <i>Vicia tetrasperma</i> and <i>V. hirsuta</i>. Much better developed ones which had convexities with the shape of a protuberance, a half-ring or a half -ring with a ligulate outgrowth were observed in <i>V. silvatica</i>, <i>V. cracca</i>, <i>V. villosa</i>, <i>V. sativa</i> and <i>V. angustifolia</i>. Completely convex, annular nectaries with a ligulate outgrowth belonged to <i>V. sepium</i> and <i>V. grandiflora</i>. Small anatomical differences concerned mainly the structure and distribution of vascular bundles, whereas ultrastructure of secretory cells was very similar. Nectar got into the surface through the modified stomata situated on the top of nectaries' convexities.

<p class="HeadingRunIn"><strong>Pheromone gland musculature in Phryganeidae: Structural features, postcopulatory modification and taxonomic significance</strong></p>

Ultrastructure of the cells forming the sternal glands in males and both fertilized and virgin females of Phryganea bipunctata Retzius and Phryganea grandis L. has been studied by optical and transmission electron microscopy. The structures involved in the synthesis and excretion of pheromone mixtures consist of 4 types of cells: secretory, canal, muscle and epidermal. The secretory and canal cells form a compound structure where the secretory cells produce the secretion, while the canal cells form the conducting and receiving cuticular canals, which participate in conducting the secretion to the cavity of a cuticular reservoir. The cuticle of the reservoir is rough and has numerous folds. Muscle fibers are situated between the epidermal cells and the secretory cells in several layers, which are perpendicular to each other. The presence of muscle fibers in pheromone glands is in agreement with the eliciting of the droplets from the gland orifice in this family. The structure of muscle fibers changes in inseminated females: they become more loose and apparently non-functional. The ultrastructure of secretory cells of the pheromone glands evidences also the greater functional activity of these glands in females as compared to the cells of males. The presence of muscle fibers in the examined pheromone glands in Trichoptera suggests these structures to be a putative apomorphy of Phryganeidae.

Development and ultrastructure of glandular trichomes inpelargonium x fragrans ‘mabel grey’ (geraniaceae)

The glandular trichomes of leaves fromPelargonium xfragrans ‘Mabel Grey’ (Geraniaceae) were examined by light, scanning, and transmission electron microscopy. These trichomes had unicellular globular heads and stalks of different lengths and features. Two types were classified: Type I, with an elongated, large head and a short (100 µm), cylindrical stalk that was more apparent on the adaxial surface; and Type II, with a spherical, small head and a long (300µm), conical stalk that was more pronounced on the abaxial surface. The ultrastructure of secretory cells from both types was distinguished by a well-developed endoplasmic reticulum, mitochondria, plastids, dictyosomes, and numerous vacuoles that likely were involved in the storage and transport of lipophilic substances. Plasmodesmata were frequent on the walls of the secretory and stalked cells. Here, we discuss the implication of structural differentiation in these trichomes.

Ultrastructure of secretory cells in the gut of the cattle-tick Boophilus microplus

The ultrastructural study of the secretory cells type 1 and 2 confirmed the separate identities of two secretory cell types in the gut of female B. microplus. Secretory cell type 1 (s 1) synthesized and secreted large, spherical, uniformly electrondense granules. Secretory cell type 2 (s 2) synthesized smaller, irregularly shaped and more complex granules. Another cell type, the basophilic cell, was shown to be the reorganized basal remnant of secretory cell s 2. A few of the basophilic cells retained remnant s 2 granules within their cytoplasm. In these cells the reorganized cisternae of rough endoplasmic reticulum were arranged in whorls and parallel arrays. The cells synthesized granules with a different ultrastructure and position in the cell from the earlier granules. The new secretory material may be egg proteins which are released into the haemolymph, and transported to the ovary. Another secretory cell type with smaller spherical granules was seen in the gut caeca of only two female ticks and more evidence is needed to prove its separate identity.

The fine structure of frontal glands in adult cestodes

Kuperman B. I. & Davydov V. G. 1982. The fine structure of frontal glands in adult cestodes. International Journal for Parasitology 12: 285–293. The localization and structure of frontal glands of adult cestodes of 20 species from 4 orders: Caryophyllidea, Pseudophyllidea, Proteocephalidea and Cyclophyllidea were studied by light and electron microscopy. In cestodes of various orders there was evidence of differences in the ultrastructure of secretory cells, in the character of the secretion, and in the method of its discharge. The localization of glands in most adult cestodes is in the scolex. In Cyatocephalus, Ligulidae, Bothriocephalus claviceps, they are distributed also in the anterior and middle part of the body. In the species Caryophylleus (C. laticeps) and Khawia sinensis a major gland complex previously not described was discovered. The glands of the cestodes investigated may be divided into three main groups by their structure, localization and functional role in ontogenesis: (1) penetration glands in oncospheres which develop into procercoids and plerocercoids; (2) glands of plerocercoids and adult cestodes which develop in the gut; (3) gland complexes in the representatives of the order Caryophyllidea. The secretion is usually discharged at the scolex region and less frequently on the lateral surface. Three different ways of discharging secretory material from the cestodes body are described.

Ultrastructural Development of Capitate Glandular Hairs of Cannabis Sativa L. (Cannabaceae)

The capitate-sessile and capitate-stalked glands of the glandular secretory system in Cannabis, which are interpreted as lipophilic type glandular hairs, were studied from floral bracts of pistillate plants. These glands develop a flattened multicellular disc of secretory cells, which with the extruded secretory product forms the gland head and the auxiliary cells which support the gland head. The secretory product accumulates beneath a sheath derived from separation of the outer wall surface of the cellular disc. The ultrastructure of secretory cells in pre-secretory stages is characterized by a dense ground plasm, transitory lipid bodies and fibrillar material, and well developed endoplasmic reticulum. Dictyosomes and dictyosome-derived secretory vesicles are present, but never abundant. Secretory stages of gland development are characterized by abundant mitochondria and leucoplasts and by a large vacuolar system. Production of the secretory product is associated with plastids which increase in number and structural complexity. The plastids develop a paracrystalline body which nearly fills the mature plastid. Material interpreted as a secretion appears at the surface of plastids, migrates, and accumulates along the cell surface adjoining the secretory cavity. Extrusion of the material into the secretory cavity occurs directly through the plasma membrane-cell wall barrier.

ULTRASTRUCTURAL DEVELOPMENT OF CAPITATE GLANDULAR HAIRS OF CANNABIS SATIVA L. (CANNABACEAE)

The capitate‐sessile and capitate‐stalked glands of the glandular secretory system in Cannabis, which are interpreted as lipophilic type glandular hairs, were studied from floral bracts of pistillate plants. These glands develop a flattened multicellular disc of secretory cells, which with the extruded secretory product forms the gland head and the auxiliary cells which support the gland head. The secretory product accumulates beneath a sheath derived from separation of the outer wall surface of the cellular disc. The ultrastructure of secretory cells in pre‐secretory stages is characterized by a dense ground plasm, transitory lipid bodies and fibrillar material, and well developed endoplasmic reticulum. Dictyosomes and dictyosome‐derived secretory vesicles are present, but never abundant. Secretory stages of gland development are characterized by abundant mitochondria and leucoplasts and by a large vacuolar system. Production of the secretory product is associated with plastids which increase in number and structural complexity. The plastids develop a paracrystalline body which nearly fills the mature plastid. Material interpreted as a secretion appears at the surface of plastids, migrates, and accumulates along the cell surface adjoining the secretory cavity. Extrusion of the material into the secretory cavity occurs directly through the plasma membrane‐cell wall barrier.

Ultrastructure of Secretory Cells in the Phloem of Mimosa pudicaL.

Ultrastructure of Secretory Cells in the Phloem of Mimosa pudicaL.

The Ultrastructure of Secretory Cells in Endometrial Cups of Pregnant Mares

Male and female differentiated fetal gonads of Equus caballus at the age of three to ten months of gestation are made up for the most part by large numbers of interstitial cells. This is in keeping with the well known fact that fetal gonads are increased in size during the above mentioned period of gestation. The gonads decrease in volume to attain a much smaller size shortly before birth. Although pregnant mare serum gonadotrophins (P.M.S.G.) determinations yielded negative results in fetal sera, the fine structure of interstitial cells is that of a hormone stimulated cell as seen in the experimental animal. At present the site of production and the way the P.M.S.G. reaches both the fetus and the mare serum is unknown. The purpose of the present paper is to postulate on morphological grounds that specialized endometrial cells present in the cups of pregnant uterus may be the site of P.M.S.G. production.

Ultrastructure of secretory cells in the pyloric gland area of the mouse gastric mucosa

Tissue specimens from the mucosa of the pyloric gland area were subjected to electron microscopic investigation in 9 fasted male albino mice. Adequate preservation was achieved by fixing with osmium tetroxide at pH 8.5 and embedding in Vestopal W. The great majority of the gland cells in the pyloric mucosa are so-called pylorus cells. On the apical surface these cells are provided with a small number of microvilli. The lateral cell surfaces form numerous interdigitations with neighboring cells. The intercellular space often exhibits dilatations of different sizes. In the apical cytoplasm a varying number of closely packed secretory granules are observed. Their average diameter is about 0.32 μ, and their content is of moderate density. The mitochondria, which have a minor axis of about 0.23 μ, sometimes contain one or two granules enclosed by the dense layers of mitochondrial inner membranes. The diameter of these granules averages 900 A. The Golgi apparatus is found in the paranuclear region and consists of flat vesicles and vacuoles. In its neighborhood secretory granules are often observed. α-Cytomembranes occur sparsely, but the free ribosomes are very numerous in the cytoplasm. Vacuole-containing bodies, dense microbodies, and fibrillar elements are other organelles in the pylorus cell cytoplasm. The nucleus is situated basally in the cell. Minor differences are observed between pylorus cells from different levels of the mucosa. Since gradual transformations occur between the different forms, there is no reason for any subdivision of the pylorus cells into different groups. Ultrastructurally the pylorus cells are indistinguishable from the mucoid fundus gland cells. Argyrophile cells are sometimes observed in the pyloric mucosa. Their ultrastructure agrees with those in other parts of the gastric mucosa. Zymogen cells and parietal cells are very rare in the pyloric gland area of the mouse.